Two-dimensional DSA series may be used to provide a color-coded visualization of the bolus arrival time (time-to-peak (TTP)), as is described for example in “syngo iFlow/Dynamic Flow Evaluation/Answers for life,” published by Siemens AG, Medical Solutions, Angiography, Fluoroscopic and Radiographic Systems, Order No. A91AX-20902-11C1-7600. Although the vascular tree may be very well visualized, it is sometimes important, in the event of stroke or vasospasm, for example, to see only the perfusion or blood circulation in the brain parenchyma. This is not possible in most cases, since the large vessels overlie the regions and may not be separated therefrom. It is not always desirable to perform a perfusion CT scan or a perfusion acquisition by rotational angiography.
If a segmentation of the parenchyma and the vessels exists, it is furthermore possible to superimpose a graphical multicomponent overlay onto the current DSA series in 2D or 3D for use as a navigation aid.
FIG. 1 depicts a single-plane X-ray system, presented by way of example, including a C-arm 2 in the form of a six-axis industrial or articulated-arm robot supported by a stand 1, to the ends of which are attached an X-radiation source, for example, an X-ray emitter 3, including X-ray tube and collimator, and an X-ray image detector 4 as image acquisition unit.
The articulated-arm robot, known for example from U.S. Pat. No. 7,500,784 B2, which may have six axes of rotation and consequently six degrees of freedom, provides the C-arm 2 to be adjusted in an arbitrary manner in space, (e.g., by the C-arm being rotated about a center of rotation between the X-ray emitter 3 and the X-ray image detector 4). The angiographic X-ray system 1 to 4 may be able to be rotated about centers of rotation and axes of rotation in the C-arm plane of the X-ray image detector 4, such as about the center point of the X-ray image detector 4 and about axes of rotation that intersect the center point of the X-ray image detector 4.
The known articulated-arm robot has a base frame that is permanently installed on a floor, for example. Attached thereto is a turntable that is rotatable about a first axis of rotation. Mounted on the turntable, so as to be pivotable about a second axis of rotation, is a robotic floating link to which is attached a robotic arm that is rotatable about a third axis of rotation. Mounted to the end of the robotic arm is a robotic hand that is rotatable about a fourth axis of rotation. To secure the C-arm 2, the robotic hand has an attachment element that is pivotable about a fifth axis of rotation and is able to be rotated about a sixth axis of rotation extending at right angles thereto.
The implementation of the X-ray diagnostic apparatus is not contingent on the industrial robot. Conventional C-arm devices may also be used.
The X-ray image detector 4 may be a flat semiconductor detector, rectangular or square in shape, which may be produced from amorphous silicon (a-Si). Integrating and possibly counting CMOS detectors may also be used.
A patient 6 to be examined is positioned as examination subject in the beam path of the X-ray emitter 3 on a tabletop platform 5 of a patient support table. Connected to the X-ray diagnostic apparatus is a system control unit 7 having an imaging system 8 that receives and processes the image signals of the X-ray image detector 4. The X-ray images may then be viewed on displays of a monitor array 10 retained by a ceiling-mounted, longitudinally displaceable, pivotable, rotatable and height-adjustable carrier system 9. Also provided in the system control unit 7 is a device 11 in which the method described herein below may be performed.
Instead of the X-ray system having the stand 1 in the form of the six-axis industrial or articulated-arm robot depicted by way of example in FIG. 1, the angiographic X-ray system may also have, as illustrated in a simplified schematic in FIG. 2, a conventional ceiling- or floor-mounted support for the C-arm 2.
Instead of the C-arm 2 depicted by way of example, the angiographic X-ray system may also have separate ceiling and/or floor-mounted supports for the X-ray emitter 3 and the X-ray image detector 4, which are coupled for example in an electronically rigid manner.
The X-ray emitter 3 emits a beam of radiation 12 that exits from a beam focus of its X-radiation source and impinges on the X-ray image detector 4. If 3D datasets are to be generated in accordance with the so-called DynaCT method, a rotational angiography method, the rotatably mounted C-arm 2 is rotated together with X-ray emitter 3 and X-ray image detector 4 such that, as FIG. 2 depicts schematically in a plan view onto the axis of rotation, the X-ray emitter 3, represented in this case illustratively by its beam focus, and the X-ray image detector 4 travel on a circular path 14 around an examination subject 13 located in the beam path of the X-ray emitter 3. The circular path 14 may be traversed completely or partially for the purpose of generating a 3D dataset or volume dataset.
The C-arm 2 together with X-ray emitter 3 and X-ray image detector 4 moves in this configuration in accordance with the DynaCT method, such as through at least an angular range of 180°, (e.g., 180° plus fan angle), and acquires projection images in quick succession from different projections. The reconstruction may be effected only from a subset of the acquired data.
The subject 13 that is to be examined may be, for example, an animal or human body, but also a phantom body.
The X-ray emitter 3 and the X-ray image detector 4 each rotate around the subject 5 in such a way that the X-ray emitter 3 and the X-ray image detector 4 are disposed on opposite sides of the subject 13.
In conventional radiography or fluoroscopy using an X-ray diagnostics apparatus, the medical 2D data of the X-ray image detector 4 is buffered in the imaging system 8 if necessary and subsequently displayed on the monitor 9.